Compared with a fluorescent lamp, an LED light source, known as a new generation of light source that is energy-saving and environment-friendly, has the advantage of smaller size, lower energy consumption, longer service life and higher lighting efficiency. At present, there are many fluorescent tubes made of LED light sources on the market to replace common fluorescent tubes. The fluorescent tubes that use LED as light sources have the advantage of quick response, high brightness, stroboflash free, noise free, long service life and good versatility, which have been widely used in homes, offices, shopping malls, public places and on transportation vehicles.
In practical applications, light from multiple light sources are usually to be mixed, and each light source may emit light with a different color. Therefore, three technical issues need to be considered, that are uniform mixing of light from different light sources, collimation of light after emitted through a light pipe and light crosstalking due to interaction of light beams. Thus, it is necessary to solve the above problems.
In the prior art, U.S. Ser. No. 13/729,459 for example relates to light mixing lenses and systems, providing an optical system. The optical system comprises a plurality of light modules disposed adjacent to one another, each of the light modules comprising a light pipe for receiving light from a light source at a proximal end thereof, guiding the received light at least partially via reflections at its one or more peripheral surfaces to a distal end thereof and providing an output surface through which light exits the light pipe, the light pipe having a non-rotationally symmetric cross-section and a lens for receiving at least a portion of the light exiting the light pipe to form an output beam, wherein each of the light modules is rotated on its longitudinal axis with respect to one or more of the other light modules, and wherein the light modules are positioned and oriented with respect to one another such that an output beam of each light module at least partially overlaps with an output beam of at least another light module over a target surface so as to provide an illumination pattern on the target surface characterized by a light distribution exhibiting a reduced appearance of a cross-sectional shape of each of the light pipes and having a cross-sectional geometry different from a cross-sectional geometry of each of the light pipes.
In the invention, the light pipe is designed to be having a non-rotationally symmetric cross-section and each of the light modules is rotated on its longitudinal axis with respect to one or more of the other light modules to change the divergence of light, so that light of different wavelengths emitted from multiple light sources can be projected as a uniform light beam after passing through the optical system. Although a certain degree of light homogenizing effect can be achieved by such method, whether light of the light sources is sufficiently and uniformly mixed more depends on the light guiding surface of the light pipe or the light sources themselves. A sufficient and uniform mixing of the light beam cannot be achieved simply by changing the cross-sectional shape of the light pipe or simply by rotating each light pipe at a certain angle. Moreover, light crosstalking will occur when light beams of multiple light pipes pass through corresponding lenses, thus affecting the projecting effect.
Accordingly, there is a need for improved optical system and light fixture.